1. Field of the Invention
This invention relates to optical measurement apparatus for dimensional measurement of a wide range of components. It offers the advantages of non-contact measurement together with flexibility since the measurements and the measuring sequence are defined in software rather than hardware.
2. Description of the Prior Art
U.K. Patent Specification No. 2058344 discloses an electro-optical apparatus for inspecting an elongate workpiece such as a camshaft having spaced lobes which is supported and turned between centres. A sensor head is provided comprising a light source, a lens for forming an image of an edge of a camshaft lobe on a photo-diode array and a read out unit. No provision is made for re-calibration of the apparatus in the course of a sequence of measurement operations on a component.
U.K. Patent application No. 2078945 also discloses an optical measurement system in which photo-detectors are used. The apparatus is particularly concerned with the methods of analysing the light pattern produced on a photo-detector array and no provision is made for re-calibration during a measurement operation.
European Patent Specification No. 0 029 748 discloses a further electro-optical measurement system for measurement of widths and possibly the thickness of a strip being rolled. Two opto-electrical transducers are arranged above the strip and each is capable of viewing substantially the entire width of the strip. A processing unit is connected to the electrical outputs of the transducers to determine the position in space of the upper edges of the two sides of the strip. Again provision is made for re-calibration when the apparatus is in use.